Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 250404
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1204 AM EDT Tue Jul 25 2017

.AVIATION...

A dry and stable environment will exist over the next 24 hours as
high pressure slowly builds into the region.  Clear skies and
light/northeast winds prevail overnight.   A low coverage of cu
possible late Tuesday.  Winds remaining modest from an easterly
direction Tuesday.

//DTW THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 343 PM EDT Mon Jul 24 2017

DISCUSSION...

A nice stretch of late July weather is set to unfold for the next
couple days as continental high pressure takes control in the Great
Lakes. Cooler northerly flow today has already scoured out the humid
air that was in place over the weekend and a little more drying is
expected tonight. This will set up comfortable overnight low
temperatures in the mid to upper 50s most locations, aided by
decreasing clouds during the evening and clear conditions by sunrise
Tuesday. Full sun to start the day will get strong surface heating
underway which will then produce just some scattered cumulus during
the afternoon. Resulting highs in the lower 80s are right about
normal for July 25th.

The mesoscale circulation aloft over the northern Plains today has
Pacific coast origins but has been enhanced by Plains convection
over the last 24-36 hours. The long wave ridge building over the
Great Lakes will steer this system through Lake Superior by Tuesday
evening and also nudge the surface high into the New England states
by Wednesday morning. The larger scale upper level features will
remain progressive thanks to the strong circulation moving through
the Canadian Rockies today that is projected to reach far northern
Ontario by Wednesday. Low level flow developing from the south will
have high pressure origins at first but then transition to southwest
and a return of moisture from the Mississippi valley by Wednesday
night. The incoming theta-e ridge has a shallow slope in the 850-700
mb layer but is building in at night for that nocturnal
destabilization factor to go along with at least some component of
low level jet forcing for moisture transport. Model QPF solutions
indicate healthy MCS signatures in the 12Z NWP package which
suggests the low level jet will be active late Wednesday night into
Thursday morning.

The upper level low tracking eastward through Canada along with a
shortwave moving along the Canadian border and a disturbance ejecting
northeastward from the Southwest US will bring the next period of
active weather to the region Thursday. These features will help
drive a cold front through Southeast Michigan with model solutions
coming into better agreement for the timing of the frontal passage.
Finer details regarding the track and timing of these disturbances
will help determine where low pressure will track and the better
forcing for thunderstorms will set up on Thursday. Current
indications are that the best forcing will be across the Detroit
Metro and areas to the south.

High pressure then builds into the region on Friday and remains in
place through the weekend keeping dry conditions in place through
Sunday. With thermal troughing residing over the region Friday
through Sunday, expect slightly cooler temperatures with highs
ranging from the 70s on Friday before slowly warming into the lower
80s on Sunday. Nighttime lows will range from the mid 50s to low 60s
during this period.

MARINE...

Northerly flow, gusting between 20 to 30 knots over the southern
Lake Huron Basin this afternoon will gradually diminish Tonight, and
drop at or below 15 knots for tomorrow as high pressure slides
through the Central Great Lakes. No changes with small craft
advisories into the evening hours. Southerly winds will return
Tuesday night and Wednesday, topping out around 20 knots as warmer
air streams back in ahead of a cold front, which may trigger showers
and thunderstorms Wednesday night into Thursday as it sags south.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 4 AM EDT early this morning for
     LHZ441>443.

Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....DG
DISCUSSION...BT/JD
MARINE.......SF


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